EFFICIENCY FORMULA of centrifugal pump n others

[striker1067]

i need the efficiency formula of centrifugal pump and other pumps. i couldnt find these in books, but the some old one.in my industry, it is not learnt, but asked. i thoroughly checked the books, but failed.kinldy give me or suggest me an appropriate book, that will be free downloadable on internet.

 

[chicopee]

get any ME (Kent or Mark) or CE (Perry) hanbook

 

[micalbrch]

Pump efficiency, ? (%) is a measure of the efficiency with wich the pump transfers useful work to the fluid.

? = Pin/Pout

where

? = efficiency (%)

Pin = power input (req. motor power)

Pout = power output (flow x pressure)

It's simpe, isn't it? But I guess that is not what you were looking for, right?

 

[IFRs]

It varies depending on where you are on the pump's performance curve. Could be somewhere between 40% and 80% roughly.

 

[chemsac2]

Formula for pump efficiency as function of specific speed is given in Pump Handbook by Igor Karassik, chapter 2, page 2.24 (equation 24).

I am attaching extract of the equation for quick reference.

An efficiency calculator is available on internet for free download. You need to know rpm, flow and head to calculate efficiency in this calculator. Calculator is based on same formula.

Regards,

Sachin

 

[striker1067]

no, this is not the right formula,it ratio of B.H.P TO W.H.P of pump, but i need the detailed formula.

 

[micalbrch]

The formular is right but perhaps not the formular you are looking for.

What do you mean with W.H.P.? Water Hore Power? If so, then it is what I described above, flow x pressure or flow x head x specific gravity.

And B.H.P.? Break Horse Power? If so, then this is the amount of horsepower going to the pump; the same that I called Pin (req. motor power) in my first reply.

And at the end of the day it goes back to the initial formular.

 

[Artisi]

striker1067 - what are you trying to find out, is this an installed operating pump or a theoretical question where you are trying to assertain an uninstalled unknown pump efficiency.

As micalbrch has already pointed out - if an installed pump you need to measure the work being done by the pump - flow x head x sg. - you then need to calculate the power input at the motor terminals, this will allow you to calculate the overall efficiency but not the pump efficiency - to establish the pump efficiency you must have the test figure for the motor to account for the motor inefficiencies which must be subtracted from the overall input power - only then can you establish the pump eficiency.

If an unistalled pump then you will have to use something like "Pump Handbook by Igor Karassik, chapter 2, page 2.24 (equation 24)" as advised by chemsac2.


Lots of luck.